JP7070498B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire in which a sound control body is arranged on the inner surface of the tread portion.

Conventionally, as a technique for suppressing running noise of a pneumatic tire, as shown in Patent Document 1, a pneumatic tire in which a sound control body made of a sponge material is arranged on the inner cavity surface of a tread portion is known.

Japanese Unexamined Patent Publication No. 2009-292461

However, in traveling in cold weather, the sound control body is hardened, and the vibration energy of air cannot be sufficiently converted into heat energy, so that the effect of reducing traveling noise is limited.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire capable of suppressing running noise even when running in cold weather.

The present invention is a pneumatic tire including a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a belt layer arranged radially outside the carcass and inside the tread portion. It has a porous sound control body arranged on the inner cavity surface of the tread portion, and is characterized in that the glass transition temperature of the sound control body is −55 ° C. to −45 ° C.

In the pneumatic tire according to the present invention, it is desirable that the density of the sound control body is 10 to 40 kg / m ³ .

In the pneumatic tire according to the present invention, it is desirable that the volume V1 of the sound control body is 0.4 to 30% of the total volume V2 of the tire lumen.

In the pneumatic tire according to the present invention, it is desirable that the tensile strength of the sound control body is 70 to 115 kPa.

In the pneumatic tire according to the present invention, the tread portion may have a vibration damping rubber body having a width W1 in the tire axial direction of 60 to 130% of a width W2 in the tire axial direction of the belt layer. desirable.

In the pneumatic tire according to the present invention, it is desirable that the vibration damping rubber body is arranged between the carcass and the belt layer.

The pneumatic tire according to the present invention has a band layer arranged radially outside the belt layer and inside the tread portion, and the vibration damping rubber body is provided between the belt layer and the band layer. It is desirable that they are arranged.

The pneumatic tire according to the present invention has a band layer arranged radially outside the belt layer and inside the tread portion, and the vibration damping rubber body is located outside the band layer in the tire radial direction. It is desirable that they are arranged.

In the pneumatic tire according to the present invention, it is desirable that the thickness of the vibration damping rubber body in the tire radial direction is 0.3 mm or more.

In the pneumatic tire according to the present invention, the relationship between the hardness H1 of the vibration damping rubber body and the hardness H2 of the tread rubber arranged on the outer side of the belt layer in the tire radial direction is 0.5 ≤ H1 / H2 ≤. It is preferably 1.0.

In the pneumatic tire according to the present invention, the loss tangent tan δ at 0 ° C. of the tread rubber arranged outside the tire radial direction of the belt layer is 0.4 or more, and the loss tangent at 70 ° C. It is desirable that tan δ is 0.2 or less.

In the pneumatic tire according to the present invention, the tread rubber arranged on the outer side of the belt layer in the tire radial direction is (1.4 × carbon black content (phr) + silica content (phr)) / sulfur content. It is desirable that the rubber composition has a value of 20 or more.

According to the pneumatic tire of the present invention, since the sound control body is arranged on the inner surface of the tread portion, the cavity resonance in the tire cavity is suppressed, and the running noise of the pneumatic tire is reduced. Further, in the present invention, since the glass transition temperature of the sound control body is −55 ° C. to −45 ° C., the flexibility of the sound control body is maintained at a low temperature. As a result, even when traveling in cold weather, the sound control body effectively converts the vibration energy of the air into heat energy, and the traveling noise is reduced.

It is sectional drawing which shows one Embodiment of the pneumatic tire of this invention. It is sectional drawing which shows another embodiment of the pneumatic tire of this invention. It is sectional drawing which shows another embodiment of the pneumatic tire of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a tire meridian including a tire rotation axis in a normal state of the pneumatic tire 1 of the present embodiment. Here, the normal state is a state in which the tire is rim-assembled on the normal rim RM and the normal internal pressure is charged, and there is no load. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATTA, "Design Rim" for TRA, and ETRTO. If so, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS". The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO. If the tires are for passenger cars, the tires will be set to 200 kPa uniformly in consideration of the actual frequency of use.

As shown in FIG. 1, the pneumatic tire (hereinafter, may be simply referred to as “tire”) 1 of the present embodiment is a carcass 6 from the tread portion 2 to the bead core 5 of the bead portion 4 via the sidewall portion 3. And a belt layer 7 arranged on the outer side of the carcass 6 in the radial direction of the tire and on the inner side of the tread portion 2. In this embodiment, those for passenger cars are shown.

The carcass 6 is composed of, for example, one carcass ply 6A. This carcass ply 6A has a series of folded portions 6b that are locked to the bead core 5 by folding around the bead core 5 from the inside to the outside in the tire axial direction at both ends of the main body portion 6a straddling between the bead cores 5 and 5. Yes. For the carcass ply 6A, for example, an organic fiber cord such as aromatic polyamide or rayon is adopted as the carcass cord. The carcass cords are arranged at an angle of, for example, 70 to 90 ° with respect to the tire equator C. The carcass ply 6A is configured by covering the plurality of carcass cords with the topping rubber. A bead apex rubber 8 extending from the bead core 5 outward in the radial direction of the tire is arranged between the main body portion 6a and the folded portion 6b.

On the outside of the carcass 6, a tread rubber Tg forming a ground contact surface, a sidewall rubber Sg forming the outer surface of the sidewall portion 3, a bead rubber Bg forming the outer surface of the bead portion 4, and the like are arranged. On the other hand, inside the carcass 6, an inner liner rubber Lg or the like for maintaining the tire internal pressure is arranged.

In the present embodiment, the belt layer 7 has two belt plies 7A and 7B in which the belt cords are arranged so as to be inclined at an angle of, for example, 15 to 45 ° with respect to the tire equator C, and the belt cords intersect each other. It is overlapped in the radial direction of the tire. For this belt cord, for example, steel, aramid, rayon, or the like is preferably adopted. The belt plies 7A and 7B are configured by covering the plurality of belt cords with the topping rubber.

In the pneumatic tire 1 of the present embodiment, the band layer 9 is arranged on the outer side of the belt layer 7 in the tire radial direction. The band layer 9 includes a band cord of organic fibers, in this example, a band ply 9A in which a nylon cord is spirally wound at an angle of 10 degrees or less, preferably 5 degrees or less with respect to the tire circumferential direction.

The pneumatic tire 1 has a sound control body 20 arranged on the lumen surface of the tread portion 2. The sound control body 20 is made of, for example, a porous sponge material. The sponge material is a sponge-like porous structure, for example, a web in which animal fibers, plant fibers, synthetic fibers, etc. are entwined and integrally connected in addition to the so-called sponge itself having open cells in which rubber or synthetic resin is foamed. It shall include the shape. Further, the "porous structure" includes not only open cells but also closed cells. For the sound control body 20 of this example, a continuous cell sponge material made of polyurethane is used.

The sponge material as described above reduces the sound (cavity resonance energy) by converting the vibration energy of the air vibrating on the surface or the internal porous portion into heat energy and consuming it, and the running noise of the pneumatic tire 1. To reduce. Further, since the sponge material is easily deformed by shrinkage, bending, etc., it does not substantially affect the deformation of the tire during traveling. Therefore, it is possible to prevent the steering stability from deteriorating. Moreover, since the sponge material has a very small specific gravity, it is possible to prevent deterioration of the weight balance of the tire.

The sponge material is preferably an ether-based polyurethane sponge, an ester-based polyurethane sponge, a synthetic resin sponge such as polyethylene sponge, a chloroprene rubber sponge (CR sponge), an ethylene propylene rubber sponge (EDPM sponge), a nitrile rubber sponge (NBR sponge), or the like. A rubber sponge can be preferably used, and a polyurethane-based or polyethylene-based sponge containing an ether-based polyurethane sponge is particularly preferable from the viewpoints of sound control, light weight, adjustable foaming, and durability.

The sound control body 20 has a long strip shape having a bottom surface fixed to the lumen surface of the tread portion 2, and extends in the tire circumferential direction. At this time, the outer end portions in the circumferential direction may be butted against each other to form a substantially annular shape, and the outer end portions may be separated from each other in the circumferential direction.

The sound control body 20 has substantially the same cross-sectional shape at each position in the circumferential direction except the outer end portion. As this cross-sectional shape, a flat and horizontally long shape having a small height with respect to the width in the tire axial direction is preferable in order to prevent the tire from falling or deforming during traveling. In particular, as in this example, it is preferable that the concave groove 21 extending continuously in the circumferential direction is provided on the inner surface side in the radial direction. The concave groove 21 can increase the surface area of the sound control body 20, absorb more resonance energy, improve heat dissipation, and suppress the temperature rise of the sponge material.

The glass transition temperature of the sound control body 20 is −55 ° C. to −45 ° C. If the glass transition temperature is less than −55 ° C., the hardness at room temperature tends to decrease, which may affect the durability. When the glass transition temperature exceeds −45 ° C., the flexibility of the sound control body 20 at a low temperature is impaired, and the reduction in running noise described above may be reduced. In the pneumatic tire 1, since the glass transition temperature of the sound control body 20 is set in the range of −55 ° C. to −45 ° C., the flexibility of the sound control body at a low temperature is maintained. As a result, the sound control body 20 effectively converts the vibration energy of the air into heat energy even when traveling in cold weather, and the traveling noise is sufficiently reduced.

In the present embodiment, the vibration damping rubber body 30 is arranged inside the tread portion 2. The vibration damping rubber body 30 is arranged between the carcass 6 and the belt layer 7. The vibration damping rubber body 30 is made of a rubber different from the topping rubber contained in the carcass ply 6A and the belt ply 7A. The width W1 of the vibration damping rubber body 30 in the tire axial direction is 60 to 130% of the width W2 of the belt layer 7 in the tire axial direction. The more desirable width W1 of the vibration damping rubber body 30 is 70 to 120% of the width W2 of the belt layer 7. Such a vibration damping rubber body 30 suppresses vibrations of the carcass 6 and the belt layer 7 without increasing the weight of the pneumatic tire 1, and contributes to reduction of running noise particularly in the vicinity of 160 Hz. If the sound damping body 20 has a sufficient effect of reducing running noise, the vibration damping rubber body 30 may be omitted.

The thickness T1 of the vibration damping rubber body 30 in the tire radial direction is preferably 0.3 mm or more. By setting the thickness T1 to 0.3 mm or more, the vibration of the tread portion 2 is suppressed more effectively. Further, by setting the maximum thickness of the vibration damping rubber body 30 in the tire radial direction to 4 to 20% of the maximum thickness of the tread portion 2, it is possible to suppress the running noise of the pneumatic tire 1 and achieve both steering stability performance. It can be easily planned.

The relationship between the hardness H1 of the vibration damping rubber body 30 and the hardness H2 of the tread rubber Tg arranged on the outer side of the belt layer 7 in the tire radial direction is preferably 0.5 ≤ H1 / H2 ≤ 1.0. Here, the "rubber hardness" is based on JIS-K6253 and is defined as the rubber hardness according to the durometer type A in an environment of 23 ° C. The vibration damping rubber body 30 having the hardness H1 ensures the durability of the tread portion 2 and suppresses the vibration of the tread portion 2 more effectively.

The relationship between the hardness H1 of the damping rubber body 30 and the hardness H3 of the topping rubber contained in the carcass ply 6A and the belt ply 7A is preferably 0.4 ≤ H1 / H3 ≤ 1.2. The vibration damping rubber body 30 having the hardness H1 ensures the durability of the tread portion 2 and suppresses the vibration of the tread portion 2 more effectively.

A more specific vibration damping rubber body 30 has a desirable hardness H1 of 30 ° to 73 °. With the vibration damping rubber body 30 having such a hardness H1, it is possible to easily suppress running noise and improve steering stability performance while suppressing the manufacturing cost of the pneumatic tire 1. Further, the desired hardness H2 of the more specific tread rubber Tg is 55 ° to 75 °. The tread rubber Tg having such a hardness H2 optimizes the rigidity of the tread portion 2 and makes it possible to improve the steering stability performance.

In the pneumatic tire 1 provided with the sound control body 20 on the inner cavity surface of the tread portion 2, the puncture repair liquid is locally absorbed by the sound control body 20 during puncture repair using the puncture repair liquid, and after the repair. The uniformity performance of the tire may deteriorate. The uniformity referred to here is the uniformity of weight including the pneumatic tire 1, the sound control body 20, and the puncture repair liquid. If such uniformity is impaired, there is a problem that running noise tends to increase. Considering the uniformity performance after puncture repair, the density of the sound control body 20 is preferably 10 kg / m ³ or more. On the other hand, the sound control body 20 having a density of 40 kg / m ³ or less makes it possible to reduce running noise particularly around 250 Hz without inviting an increase in the weight of the pneumatic tire 1.

The volume V1 of the sound control body 20 is preferably 0.4 to 30% of the total volume V2 of the tire lumen. The volume V1 of the sound control body 20 is the apparent total product of the sound control body 20, and means the volume determined from the outer shape including the bubbles inside. The total volume V2 of the tire lumen shall be approximately obtained by the following formula in a normal state with no load in which a pneumatic tire is rim-assembled on a regular rim and filled with a regular internal pressure.
V2 = A × {(Di-Dr) / 2 + Dr} × π
Here, in the above formula, "A" is the cross-sectional area of the tire cavity obtained by CT scanning the tire / rim assembly in the normal state, and "Di" is the maximum outside of the tire cavity surface in the normal state. The diameter, "Dr" is the rim diameter, and "π" is the pi.

If the volume V1 is less than 0.4% of the total volume V2, the vibration energy of air may not be sufficiently converted. When the volume V1 exceeds 30% of the total volume V2, the weight and manufacturing cost of the pneumatic tire 1 become large. In addition, when repairing a flat tire using a flat tire repair liquid, the uniformity performance after the repair may deteriorate.

The tensile strength of the sound control body 20 is preferably 70 to 115 kPa. If the tensile strength of the sound control body 20 is less than 70 kPa, the durability performance of the sound control body 20 may deteriorate. When the tensile strength of the sound control body 20 exceeds 115 kPa, or when a foreign substance such as a nail is stuck in the area including the sound control body 20 of the tread portion 2, the sound control body 20 is pulled by the foreign matter and is inside the tread portion 2. There is a risk of peeling from the cavity surface.

The loss tangent tan δ of the tread rubber Tg at 0 ° C. is preferably 0.4 or more. This improves the wet grip performance of the pneumatic tire 1. Therefore, for example, the running noise can be further reduced by setting the volume of the groove formed on the ground contact surface of the tread portion 2 to be small. The loss tangent tan δ of the tread rubber Tg at 70 ° C. is preferably 0.2 or less. As a result, the rolling resistance of the pneumatic tire 1 is suppressed, and the deterioration of fuel efficiency performance due to the provision of the sound damping body 20 and the vibration damping rubber body 30 is suppressed. The loss tangent tan δ at 0 ° C and the loss tangent tan δ at 70 ° C are measured at each measurement temperature (0 ° C or 70 ° C) using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. in accordance with the provisions of JIS-K6394. ), Frequency 10 Hz, initial stretch strain 10%, and dynamic strain amplitude ± 2%.

It is desirable that the tread rubber Tg has a value of (1.4 × carbon black content (phr) + silica content (phr)) / sulfur content (phr) of 20 or more. This improves wear resistance. Therefore, for example, by setting the groove formed on the ground contact surface of the tread portion 2 to be shallow, running noise can be further reduced. Further, even when the distribution of the puncture repair liquid is uneven, the occurrence of uneven wear is suppressed.

Although the pneumatic tire of the present invention has been described in detail above, the present invention is not limited to the above-mentioned specific embodiment, but is modified to various embodiments.

For example, FIG. 2 shows a pneumatic tire 1A, which is another embodiment of the present invention. The pneumatic tire 1A is different from the pneumatic tire 1 in that the vibration damping rubber body 30 is arranged between the belt layer 7 and the band layer 9. The configuration of the pneumatic tire 1 may be adopted for the portion of the pneumatic tire 1A not described below. In the pneumatic tire 1A, the vibration of the belt layer 7 and the band layer 9 is suppressed by the vibration damping rubber body 30, and the vibration of the tread portion 2 is suppressed.

FIG. 3 shows a pneumatic tire 1B, which is still another embodiment of the present invention. The pneumatic tire 1B is different from the pneumatic tire 1 in that the vibration damping rubber body 30 is arranged outside the band layer 9 in the tire radial direction. The configuration of the pneumatic tire 1 may be adopted for the portion of the pneumatic tire 1B not described below. In the pneumatic tire 1B, the vibration damping rubber body 30 suppresses the vibration of the band layer 9 and the tread rubber Tg, and thus the vibration of the tread portion 2 is suppressed.

A pneumatic tire of size 165 / 65R18, which forms the basic structure of FIG. 1, was prototyped based on the specifications in Table 1 and tested for noise performance in a low temperature environment. The specifications common to each embodiment and comparative example are as follows.
(1) Tread rubber ・ The composition is as follows.
Natural rubber (TSR20): 15 (phr)
SBR1 (Amount of bound styrene: 28%, vinyl group content 60%, glass transition point -25 ° C, terminal modification): 45 (phr)
SBR2 (Amount of bound styrene: 35%, Vinyl group content 45%, Glass transition point -25 ° C, Terminal denaturation): 25 (phr)
BR (BR150B, Ube): 15 (phr)
Carbon black N220: 5 (phr)
Silica (VN3): 35 (phr)
Silica (1115MP): 20 (phr)
Silane coupling agent Si266: 4 (phr)
Resin (SYLVARES SA85, Arizona Chemical Co., Ltd.): 8 (phr)
Oil: 4 (phr)
Wax: 1.5 (phr)
Anti-aging agent (6C): 3 (phr)
Stearic acid: 3 (phr)
Zinc oxide: 2 (phr)
Sulfur: 2 (phr)
Vulcanization accelerator (NS): 2 (phr)
Vulcanization accelerator (DPG): 2 (phr)
-The hardness of the tread rubber in the tire after vulcanization is 64 °.
-The maximum thickness of the tread rubber is 10 mm.
(2) Vibration damping rubber body ・ The composition is as follows.
Natural rubber (TSR20): 65 (phr)
SBR (Nipol 1502): 35 (phr)
Carbon black N220: 52 (phr)
Oil: 15 (phr)
Stearic acid: 1.5 (phr)
Zinc oxide: 2 (phr)
Sulfur: 3 (phr)
Vulcanization accelerator (CZ): 1 (phr)
-The hardness of the vibration damping rubber body in the tire after vulcanization is 58 °.
-The maximum thickness of the damping rubber body is 1 mm.
(3) Sound control body ・ Volume is 15% of the total volume of the tire lumen.
-The density is 27 kg / m ³ .
(4) Belt cord ・ The angle of the belt cord with respect to the tire equator is 41 °.
The test method is as follows.

<Noise performance>
Each test tire was mounted on a rim 18 × 7JJ and brought into a test room where the room temperature was set to −50 ° C. Each test tire runs at a speed of 60 km / h on a drum having a replica road surface with a diameter of 3.3 m under the condition of an internal pressure of 320 kPa and a load of 4.8 kN, and is 25 mm forward and 25 mm in height from the grounded tread surface. Sound pressure level (dB) at distant positions was measured by a microphone. The result is represented by an exponent with Example 1 as 100, and the larger the value, the smaller the running noise and the better.

As is clear from Table 1, it was confirmed that the pneumatic tires of Examples 1 to 3 had significantly improved noise performance in a low temperature environment as compared with Comparative Examples 1 and 2.

Further, as shown in Table 2, the pneumatic tires of Examples 4 to 8 were prototyped and tested for noise performance in a low temperature environment. The test method is as follows.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an index with Example 5 as 100, and the larger the value, the smaller the running noise and the better.

Further, as shown in Table 3, the pneumatic tires of Examples 9 to 12 were prototyped and tested for noise performance and steering stability performance in a low temperature environment. The test method is as follows.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an exponent with Example 11 as 100, and the larger the value, the smaller the running noise and the better.

<Maneuvering stability performance>
Each test tire is mounted on the rim 18x7JJ, mounted on all wheels of the vehicle (domestic 2500cc FR car) under the condition of internal pressure 320kPa, runs on the dry asphalt test course, steering wheel responsiveness, rigidity, The characteristics related to the grip etc. were evaluated by the sensory evaluation of the driver. The evaluation is based on a score of 100 in Example 11, and the larger the value, the better.

Further, as shown in Table 4, the pneumatic tires of Examples 13 to 17 having different rubber hardnesses of the vibration damping rubber bodies were prototyped, the noise performance in a low temperature environment was tested, and the manufacturing cost was calculated. The test method and calculation method are as follows.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an exponent with Example 15 as 100, and the larger the value, the smaller the running noise and the better.

<Manufacturing cost>
The manufacturing cost required to manufacture one tire was calculated. The result is represented by an index with Example 15 as 100, and the larger the value, the smaller the manufacturing cost and the better.

Further, as shown in Table 5, the pneumatic tires of Examples 18 to 22 were prototyped and tested for uniformity performance after puncture repair and noise performance in a low temperature environment. The test method is as follows.

<Uniformity performance>
After each test tire is mounted on the rim 18x7JJ and filled with puncture repair material assuming puncture repair, radial force is compliant with JASO C607: 2000 uniformity test conditions under the condition of internal pressure 320kPa. Variation (RFV) was measured. The evaluation speed is 10 km / h. The result is expressed by an index with Example 20 as 100, and the larger the value, the smaller the RFV and the better.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an index with Example 20 as 100, and the larger the value, the smaller the running noise and the better.

Further, as shown in Table 6, the pneumatic tires of Examples 23 to 27 were prototyped, and the uniformity performance after puncture repair and the noise performance in a low temperature environment were tested. The test method is as follows.

<Uniformity performance>
RFV was measured by the same method as above. The result is expressed by an exponent with Example 25 as 100, and the larger the value, the smaller the RFV and the better.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an index with Example 25 as 100, and the larger the value, the smaller the running noise and the better.

Further, as shown in Table 7, the pneumatic tires of Examples 28 to 32 were prototyped, and the durability performance of the sound control body and the peeling resistance performance of the sound control body at the time of nailing were tested. The test method is as follows.

<Durability of sound control body>
Each test tire is mounted on the rim 18 × 7JJ, and the distance until the sound control body and its vicinity are damaged under the conditions of internal pressure 320kPa, load 4.8kN, speed 80km / h using a drum tester. It was measured. The result is displayed as an exponent with the value of Example 30 as 100. As for the evaluation, the larger the numerical value, the higher the durability performance and the better.

<Peeling resistance of the sound control body when stepping on a nail>
Each test tire mounted on the rim 18x7JJ is punctured by nailing, and by disassembling the damaged part, the area where the sound control body pulled by the nail is peeled off from the inner surface of the tread is measured. Was done. The result is displayed as an index with the value of Example 30 as 100, and the larger the numerical value, the higher the peeling resistance performance and the better.

Further, as shown in Table 8, the pneumatic tires of Examples 33 to 35 were prototyped and tested for noise performance in a low temperature environment. The test method is as follows.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an exponent with Example 1 as 100, and the larger the value, the smaller the running noise and the better.

Further, as shown in Table 9, the pneumatic tires of Examples 36 to 40 were prototyped and tested for uniformity performance after puncture repair and noise performance in a low temperature environment. The test method is as follows.

<Uniformity performance>
Radial force variation (RFV) was measured by the same method as above. The result is expressed by an index with Example 20 as 100, and the larger the value, the smaller the RFV and the better.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an index with Example 20 as 100, and the larger the value, the smaller the running noise and the better.

Further, as shown in Table 10, the pneumatic tires of Examples 41 to 45 were prototyped and tested for uniformity performance after puncture repair and noise performance in a low temperature environment. The test method is as follows.

<Uniformity performance>
Radial force variation (RFV) was measured by the same method as above. The result is expressed by an exponent with Example 25 as 100, and the larger the value, the smaller the RFV and the better.

<Noise performance>
The sound pressure level was measured by the same method as above. The result is represented by an index with Example 25 as 100, and the larger the value, the smaller the running noise and the better.

1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 20 Sound damping body 30 Vibration damping rubber body

Claims (12)

The carcass from the tread part to the bead core of the bead part through the sidewall part,
A belt layer arranged radially outside the carcass and inside the tread portion,
A pneumatic tire provided with a tread rubber arranged on the outer side of the belt layer in the radial direction of the tire.
The loss tangent tan δ of the tread rubber at 0 ° C. measured under the conditions of a frequency of 10 Hz, an initial stretch strain of 10%, and a dynamic strain amplitude of ± 2% is 0.4 or more.
It has a porous sound control body arranged on the luminal surface of the tread portion, and has.
A pneumatic tire characterized in that the glass transition temperature of the sound control body is −55 ° C. to −45 ° C. The pneumatic tire according to claim 1, wherein the sound control body has a density of 10 to 40 kg / m ³ . The pneumatic tire according to claim 1 or 2, wherein the volume V1 of the sound control body is 0.4 to 30% of the total volume V2 of the tire lumen. The pneumatic tire according to any one of claims 1 to 3, wherein the sound control body has a tensile strength of 70 to 115 kPa. The air according to any one of claims 1 to 4, wherein the air damping rubber body having a width W1 in the tire axial direction is 60 to 130% of the width W2 in the tire axial direction of the belt layer inside the tread portion. Tires with tires. The pneumatic tire according to claim 5, wherein the vibration damping rubber body is arranged between the carcass and the belt layer. It has a band layer arranged radially outside the belt layer and inside the tread portion.
The pneumatic tire according to claim 5, wherein the vibration damping rubber body is arranged between the belt layer and the band layer. It has a band layer arranged radially outside the belt layer and inside the tread portion.
The pneumatic tire according to claim 5, wherein the vibration damping rubber body is arranged outside the band layer in the radial direction of the tire. The pneumatic tire according to any one of claims 5 to 8, wherein the thickness of the vibration damping rubber body in the tire radial direction is 0.3 mm or more. The pneumatic tire according to any one of claims 5 to 9, wherein the relationship between the hardness H1 of the vibration damping rubber body and the hardness H2 of the tread rubber is 0.5 ≤ H1 / H2 ≤ 1.0. The air-filled tire according to any one of claims 1 to 10, wherein the loss tangent tan δ at 0 ° C. of the tread rubber is 0.4 or more, and the loss tangent tan δ at 70 ° C. is 0.2 or less. tire. The tread rubber is any of claims 1 to 11 which is a rubber composition having a value of (1.4 × carbon black content (phr) + silica content (phr)) / sulfur content (phr) of 20 or more. Pneumatic tires listed in silica.

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